Comparative Studies on the Rate of Circum- 
nutation of Some Flowering Plants. 
By EizaBetH A. Simons. 
URING the spring term of session 1897-98 the Senior 
and Post-Graduate students of the Botanical Depart- 
ment began, under the direction of Professor Macfar- 
lane, a series of experiments on the circumnutation of stems, for 
comparison of the results with those obtained by Darwin* 
and more recently in the Botanic Garden of the University 
by Dr. A. Schively.t 
The writer was asked to continue and extend these results, 
for five plants specially recorded by Darwin. These are Con- 
volvulus Sepium, Phaseolus vulgaris, Lonicera brachypoda, 
(L. japonica), Wistaria chinensis, and Humulus Lupulus. Marks 
were made at frequent time-intervals on a plate of glass placed 
directly above the circumnutating tip, and permanent graphic 
records have been prepared from them. The tables appended 
to this paper have been compiled from these. 
The shoots were carefully tied to a support, and in most 
cases three internodes were left free. The records extended 
over a period of about six months, and thus included times 
when the sun gave considerable differences of light intensity 
and of temperature. In this paper no account is taken of light 
intensity, though data are being gathered which indicate that 
this is a factor in circumnutation, as is also the relative hygro- 
metric condition of the atmosphere. It is somewhat unfortu- 
nate that few details are given by Darwin as to environmental 
conditions, but the writer regards the relatively higher tem- 
perature that prevailed during her studies as the main factor 
* Power of Movement in Plants. 
¢ Bot. Contrib. Univ. Penn. Vol. I. 
66 
